organisation

• a tissue is a group of similar cells that work together to carry out a particular function
• an organ is a group of different tissues that work together to perform a certain function
• an organ system is a group of organs working together to perform a particular function
• organ systems work together to make entire organisms
• a catalyst is a substance that increases the rate of a chemical reaction without being used up in the reaction
• when an enzyme is denatured, the active site changes shape and the substrate cannot fit
• enzymes need the right temperature and pH
• alveoli carry out gas exchange in the body
• CHAMBERS OF THE HEART :

  • left atrium
  • right atrium
  • left ventricle
  • right ventricle
• BLOOD FLOW:

  1. blood flows into the 2 atria from the vena cava and the pulmonary vein
  2. the atria contract pushing the blood into the ventricles
  3. the ventricles contract forcing the blood into the pulmonary artery and the aorta, and out of the heart
  4. the blood then flows to the organs through arteries and returns through veins
• arteries called the coronary arteries branch off the aorta and surround the heart, making sure it gets all the oxygenated blood it needs
• arteries carry the blood away from the heart
• capillaries are involved in the exchange of materials at the tissues
• veins carry blood to the heart and have a thinner wall than arteries
• artery walls are strong and elastic, and the hole in the middle is the lumen
• capillary walls are only one cell thick, and have a very small lumen
• veins have a large lumen, valves and thin walls to allow blood to flow quickly
• red blood cells carry oxygen
• white blood cells defend against infection
• platelets help blood clot and form scabs to stop bleeding
• plasma is the liquid that carries everything in blood
• plasma carries :

  • red and white blood cells and platelets
  • nutrients like glucose and amino acids
  • carbon dioxide
  • urea
  • hormones
  • proteins
  • antibodies and antitoxins
• cardiovascular disease are diseases of the heart and blood vessels eg. coronary heart disease
• stents are tubes inserted inside arteries to keep them open, lowering the risk of a heart attack
• stents + :

  1. effective for a long time
  2. recovery is quick
• stents - :

  1. risk of infection from surgery
  2. risk of developing a blood clot near the stent (thrombosis)
• statins reduce cholesterol in the blood and reduce the risk of heart attacks
• statins + :

  1. can also help to prevent other diseases
  2. reduce risk of strokes and heart attacks
• statins - :

  1. long term drug that must be take regularly
  2. sometimes cause negative side effects
• health is a state of physical and mental wellbeing
• risk factors are things that are linked to an increase in the likelihood that a person will develop a disease
• RISK FACTORS THAT CAN CAUSE A DISEASE DIRECTLY :

  1. smoking = cardiovascular disease
  2. obesity = type 2 diabetes
  3. alcohol = liver disease
  4. radiation = cancer
• CANCER:

  benign = the rumour grows until there is no more room, stays in one place and isnt cancerous
• CANCER :

  malignant = the tumour grows and spreads into healthy tissues, they are cancerous
• plants are made of organs like stems, roots and leaves
• plant organs work together to make organ systems which perform the various tasks of the plant
• meristem tissues is found at the growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell
• phloem tubes transport food substances (dissolved sugars) from the leaves to the rest of the plant. this process is called translocation
• xylem tubes take water up from the roots to the leaves and transport it to the stomata. this process is called the transpiration stream
• transpiration is the loss of water from a plant by evaporation from the surface of the leaf